Lifting mechanism for a bed deck

ABSTRACT

A lifting mechanism is disclosed for a bed deck having a top surface where a user may lie thereon and a bottom surface. The bed deck is rotatably mounted to a bed platform having a recessed storage area. The bed deck can be moved from a horizontal to a non-horizontal position. The lifting mechanism is at least partially disposed in the recessed storage area and includes a torsion bar having a first end and a second end; a cam follower rigidly mounted to the torsion bar proximal to the first end; an anchor arm rigidly mounted to the torsion bar proximal to the second end; a mechanism for mounting the torsion bar with the bed platform; and a cam mounted to the bottom surface of the bed deck.

RELATED APPLICATIONS

This application is a non-provisional patent application of U.S. patent application Ser. No. 60/473,630, Filed May 27, 2003, entitled “Lifting Mechanism For A Bed Deck” and is a continuation-in-part of U.S. patent application Ser. No. 10/391,091, filed Mar. 18, 2003, which is a continuation-in part of U.S. Pat. No. 6,611,973, issued Sep. 2, 2003 the disclosures of which are incorporated herein by reference.

BACKGROUND

U.S. Application Ser. No. 10/146,153 (the '153 application), filed May 15, 2002, for a “Bed Structure with Storage Area”, and assigned to the same assignee as that of the present invention, is incorporated herein by reference. The '153 application discloses a bed structure with a platform having a recessed storage area and a deck hingedly mounted to the platform such that the same may serve as a surface upon which a user may lie (e.g., for sleeping), and may be rotated upward for access to the storage area. FIG. 1 shows one embodiment of a bed structure 10 having one or more platforms 12 disposed in spaced relation to one another by a set of end frames 14. Each platform 12 has a recessed storage area 16 formed therein by sidewalls 18 of the platform 12. A deck 20 is rotatably mounted to the platform 12 to alternately cover the recessed storage area 16 and provide access to the storage area 16.

Depending on the construction of the deck 20, it may have a weigh well over 100 pounds, and in one embodiment of the bed structure 10 the deck 20 weights over 190 pounds. Not only does this make it difficult to manually rotate the deck 20 upward, but also presents a serious danger of the deck accidentally falling downward if the deck is “propped-up” to hold open the access to the recessed storage area 16. Although lifting mechanisms for such decks 20, such as gas springs 22, have been proposed for assisting in deck lifting, the high forces needed for upward rotation of the deck 20 from the most downward position would require a very strong gas spring arrangement. Further, gas springs 22 often require maintenance over time and typically wear out within a certain number of cycles. Additionally, these types of lifting mechanisms often do not support holding up the deck 20 at a selected angle of rotation other than a fully “open” position.

SUMMARY

A lifting mechanism 100 for a bed deck 200 rotatably mounted on a bed platform 202 is provided in the form of a torsional assembly. The lifting mechanism 100 includes a cam 102 mounted on the bed deck 200 and a cam follower 104 mounted with a torsion bar 106 that is itself preferably mounted with the bed platform 202 in a recessed storage area 204 thereof. The cam 102 is configured such that the force generated by torsion of the torsion bar 106 and applied by the cam follower 104 to the cam 102 as a lifting force is reduced as the bed deck 200 is rotated upward from the horizontal position. This reduction in the lifting force value is due to the center of gravity of the rotating bed deck 200 moving into a more favorable position closer to the location where the beck deck 200 is mounted with the bed platform 202. In this way, the position of the bed deck 200 may be maintained in force equilibrium at any angle of rotation (e.g., slightly open, fully open, etc.).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a bedding assembly having a lifting assembly using gas springs;

FIG. 2 is a perspective view of the lifting mechanism in accordance with an embodiment of the present invention;

FIG. 3 is an exploded view of the lifting mechanism of the present invention;

FIG. 4 is a perspective view of the cam assembly in accordance with an embodiment of the present invention;

FIG. 5 is a cross-sectional view of the platform and deck of the present invention showing the deck in horizontal position and having a side wall cut-away to show the lifting mechanism in the platform;

FIG. 6 is a side elevational of the platform and deck of the present invention showing the deck in a non-horizontal position and having a side wall cut-away to show the lifting mechanism in the platform;

FIG. 7 is a side elevational of the platform and deck of the present invention showing the deck in a non-horizontal position and having a side wall cut-away to show the lifting mechanism in the platform;

FIG. 8 is a perspective view of the platform with lifting assembly of the present invention with the deck removed;

FIG. 9 is a perspective view of the platform with lifting assembly of the present invention with the deck removed;

FIG. 10 is a perspective view of one side of the lifting mechanism as mounted to the bed platform within the recessed storage area;

FIG. 11 is a perspective view of the other side of the lifting mechanism as mounted to the bed platform within the recessed storage area; and

FIG. 12 is a perspective view of the bed platform with the lifting mechanism removed.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 2 shows the lifting mechanism 100 without the cam 102 and removed from mounting within the recessed storage area 204 of the bed platform 202. The lifting mechanism 100 comprises generally the torsion bar 106 with the cam follower 104 rigidly mounted to a first end 108 thereof and an anchor arm 110 rigidly mounted to a second end 112 thereof. When mounted with the bed platform 202, the torsion bar 106 axis extends generally in the horizontal plane and defines a lateral direction.

Despite the fact that the mounting of the cam follower 104 with the torsion bar 106 is rigid, the cam follower 104 is able to rotate about the axis of the torsion bar due to the twisting of the bar 106 in torsion; the twisting of the torsion bar 106 is at a maximum at the first end 108 thereof where the cam follower 104 is mounted. In the embodiment shown in FIG. 1, the rotational force applied by the cam follower 104 is in a clockwise direction around the axis of the torsion bar 106. The anchor arm 110 provides a brace to prevent the torsion bar 106 from untwisting at the second end 112 thereof and releasing the torque built up in the torsion bar 106 by rotation of the cam follower 104.

To anchor the torsional bar 106 and the cam follower 104 and anchor arm 110 mounted thereon to the bed platform 202, a pair of mounting blocks 114 and a mounting plate 116 are fit onto the cam follower 104 and the anchor arm 110, respectively, and generally surround the torsion bar 106 through central holes 117 therein, as seen in FIGS. 1 and 2. The mounting blocks 114 are preferably mirror-images of one another and have abutting mating surfaces 118. Bores 120 extend laterally through the mounting blocks 114 through which fasteners may be inserted to secure the blocks 114 together and to the bed platform 202, as explained more fully herein. In this way, the mounting blocks 114 laterally sandwich a base 122 of the cam follower 104 therebetween while circumferentially surrounding bosses 124 of the base 122 through which the torsion bar first end 110 extends. Similarly, the mounting plate 116 is configured to circumferentially surround a boss 126 of the anchor arm 110 through which the torsion bar second end 112 extends. Bores 128 extend laterally through the mounting plate 116 through which fasteners extend to secure the plate 116 to the bed platform 202. Additionally, sleeve bearings 130 are press fit into the central holes 117 of the mounting blocks 114 and the mounting plate 116 and are configured to surround the bosses 124, 126 to carry the torsional on the cam follower 104 and the anchor arm 110 while allowing relatively free rotation of the follower 104 and arm 110 with respect to the blocks 114 and the plate 116, respectively.

As best seen in FIG. 3, the torsion rod 106 is preferably formed by affixing multiple elongate hexagonal rods 132 together along longitudinal surfaces thereof such that each rod contacts at least two other rods. Three hexagonal rods 132 are shown in the embodiment of FIG. 2, but any number could be used as a matter of design choice depending on the desired strength and torsional rigidity of the torsional rod 106, as well as the force necessary to lift and rotate the bed deck 200 hingedly mounted with the bed platform 202. The bosses 124, 126 of the mounting blocks 114 and the mounting plate 116, respectively, are shaped with a cross-section configured to accept the torsion rod 106.

The cam follower 104 has a body section 134 from which the base 122 extends, a pair of flanged ears 134 on an end of the body section opposite of the base 112, and a roller 136 rotatably mounted with the ears 134. The roller 136 allows the follower 104 to pass along the engaging surface 138 of the cam 102 with minimal friction while transferring the torsional load generated by the torsion bar 106 as a point load onto the cam 102.

FIG. 4 shows one embodiment of the cam 102. The engaging surface 138 is formed by a central convex region 140 that transitions into a lower concave region 142 which terminates in a stop 144. As shown in FIGS. 5 and 6, the convex region 140 is contacted by the cam follower 104 when the bed deck 200 is in the horizontal position overlying the recessed storage area 204 of the bed platform 202 and as the deck 200 rotates upward about a hinge 205 for a distance. With continued upward rotation of the bed deck 200, the roller 136 of the cam follower 104 enters the concave region 142 and continues therein until reaching the stop 144, as shown in FIG. 7. The stop 144 forms the concave region 142 with a radius that lowers in value until the radius is as small as the radius of the roller 136, effectively locking the roller 136 from continuing down the engaging surface and affixing the upward rotation limit for the bed deck 200. The cam 102 has a set of laterally extending bores 146, best seen in FIG. 4, for mounting of the cam 102 with fasteners to a bracket 148 affixed to the bed deck 200, as seen in FIGS. 5-7. A flat upper surface 150 of the cam 102 is mounted against the deck 200 to transfer the point load applied by the cam follower 104 to the deck 200.

As seen in FIGS. 5-7, the anchor arm 110 has a lower surface 152 that contacts a force adjusting screw 154 and transfers the reactive torque at the second end 112 of the torsion bar 106 opposite of the torque on the cam follower 104 to the screw 154. The screw 154 is threadingly mounted to a brace 156 on the bed platform 202 that is configured to spread the reactive torsion load in the torsion bar 106 across a reinforced surface area of the platform 202 such that the anchor arm 110 does not “blow-out” the base surface 206 of the platform 202. The screw 154 may be rotated to change the angle of the anchor arm 110 about the torsion bar axis relative to the angle of the cam follower 104 about the torsion bar axis, which increases or decreases—depending on the direction of screw 154 rotation—the force applied by the follower 104 to the cam 102.

FIGS. 8 and 9 show views of one bed platform 202 with the deck removed 200 for better viewing of the lifting mechanism 100. The mounting blocks 114 and mounting plate may, in one embodiment, be attached with fasteners to dividers 208, 210, respectively, extending orthogonally with respect to the torsion bar 106 across the base surface 206 of the bed platform 202.

FIGS. 10 and 11 show close-up views of FIGS. 8 and 9, respectively, where the lifting mechanism 100 is seen mounted to the bed platform 202 within the recessed storage area 204. A first C-shaped bracket 156 is affixed on edges thereof to a back wall 212 and the base surface 206 of the bed platform 202, such that the mounting blocks 114 may be mounted to the bracket 156—with fasteners through bores 120 in the blocks 114—between the bracket 156 and the divider 208. Likewise, a second C-shaped bracket 158 is affixed to the surfaces of the bed platform in the same configuration as the first bracket 156, such that the mounting plate 116 may be mounted to the bracket 158—with fasteners through bores 128 in the plate 116—between the bracket 158 and the divider 210. To further stabilize the first and second C-shaped brackets 156, 158, a vertical brace 160 may be mounted to the base surface 206 to span the lateral dimension between the brackets 156, 158. Also, a channel brace 162, with a cross-section best seen in FIGS. 5-7, may be mounted to the back wall 212 of the bed platform 202 to abut the top of the brackets 156, 158 and provide further stabilization thereof.

When initially loading the torsion bar 106 with the necessary torsion for lifting the bed deck 200, the cam follower 104 should be secured in a “loaded” position. To accomplish this, a loading cam (not shown) with dimensions larger than the cam 102 is first mounted to the bed deck 200 mounted to the bed platform 202. The bed deck 200 is then lowered to the horizontal position such that the weight of the bed deck 200 loads the bar 106 with torsion. Once the body section 134 of the cam follower 104 passes below an axis formed between bores 164 of adjacent loading brackets 166 (the loading cam being shaped not to block this axis as it is contacting the cam follower roller 136), a pin may be inserted through both holes to hold the loaded cam follower 104 in place. The bed deck 200 may then be lifted and the loading cam replaced with the cam 102 used for standard operation. At that point, the deck 200 is again lowered to the horizontal position, this time with the engaging surface 138 of the cam 102 contacting the cam follower roller 136. Once contact is established and the load is taken off of the loading bracket pin, the pin can be removed and the bed deck 200 and bed platform 202 are ready for use.

FIG. 12 is the same view as that of FIG. 8, but with the torsion rod 106, the cam follower 104, the anchor arm 110, the mounting blocks 114 and the mounting plate 116 removed. The position of the loading brackets 166, the C-shaped bracket 156, the vertical brace 160 and the channel brace 162 is best seen in relation to the overall configuration of the bed platform 202 in FIG. 12.

Observing the motion of the bed deck 200 in FIGS. 5-7, it may be seen that as the deck is rotated upward from the horizontal position, the center of gravity C_(G) of the deck 200 moves towards a vertical plane aligned with the hinge 205 axis about which the deck 200 rotates. Thus, less of a moment exists that must be overcome by the point load applied by the cam follower 104. Consequently, when the deck is at or near the horizontal position, the cam follower 104 is rotated to a lower position corresponding to increased torsion in the torsion bar 106. As the deck rotates upward, FIGS. 6 and 7 show the cam follower 104 likewise rotating upward, because of the shape of the cam engaging surface 138, decreasing the torsion in the torsion bar 106; the decreased torsion is desired because of the lower moment needed to support the bed deck 200 at the rotated position in force equilibrium. If the cam engaging surface 138 is properly dimensioned, and the weight of the bed deck 200 is known, the point load applied to the deck 200 by the cam follower 104 will equal the moment produced by the deck 200, hence force equilibrium, and the deck 200 can be suspended at any angle of rotation without having to hold or brace the deck 200. Even if additional items are placed on the deck 200, increasing the moment, if the weight of these items is small compared to the weight of the deck 200, only a small lifting force will be necessary to lift the deck and expose the recessed storage area 304.

It should also be understood that the key lifting components of the lifting mechanism 100 may be reversed in position. In this arrangement, the torsion rod 106 is mounted on the undersurface of the bed deck 200 with the cam follower 104 and anchor arm 110 affixed on the rod 106 and facing a direction opposite of that shown in FIGS. 8-11. Likewise, the flat upper surface 150 of the cam 102 becomes a bottom surface mounted against the platform base surface 206 such that the cam 102 faces upward for engagement with the cam follower 104 facing downward. 

1. A lifting mechanism for a bed deck having a top surface where a user may lie thereon and a bottom surface, the bed deck being rotatably mounted with a bed platform having a recessed storage area for movement of the bed deck from a horizontal to a non-horizontal position, the lifting mechanism being at least partially disposed in the recessed storage area, and comprising: a torsion bar having a first end and a second end; a cam follower rigidly mounted on the torsional bar proximal to the first end; an anchor arm rigidly mounted on the torsional bar proximal to the second end; means for mounting the torsional bar with the bed platform; a cam mounted to the bottom surface of the bed deck whereby a torsional force in the torsion bar generated by the rotation of the cam follower about an axis of the torsion bar and relative to the position of the anchor arm is transferred by the cam follower to the cam to provide a biasing force to the bed deck in the direction of rotation thereof from the horizontal to the non-horizontal position.
 2. The lifting mechanism of claim 1, wherein the cam has an engaging surface that is contacted by the cam follower to transfer the torsional force on the cam follower as a point load to the cam, the engaging surface configured with a profile such that as the bed deck is rotated away from the horizontal position, the point load is reduced a specified amount such that the bed deck may be suspended in force equilibrium at a range of non-horizontal positions.
 3. The lifting mechanism of claim 1, further comprising a force adjusting screw threadingly mounted with the bed platform, wherein the anchor arm is positioned to abut the screw and transfer a reactive torque opposite of the torque on the cam follower to the screw, and wherein rotation of the screw changes the angle of the anchor arm about an axis of the torsion bar relative to the position of the cam follower to adjust the biasing force applied to the bed deck through the range of non-horizontal positions.
 4. The lifting mechanism of claim 1, wherein the cam follower has at least one boss and the anchor arm has a boss, and wherein the means for mounting the torsional bar with the bed platform comprises: at least one mounting block having a central hole therethrough; a sleeve bearing fit within the central hole of each mounting block and having an inner diameter sized to receive the boss of the cam follower; a mounting plate having a central hole therethrough; a sleeve bearing fit within the central hole of the mounting plate and having an inner diameter sized to receive the boss of the anchor arm; a first bracket affixed to the bed platform within the recessed storage area with which the at least one mounting block is mounted; and a second bracket affixed to the bed platform within the recessed storage area with which the mounting plate is mounted.
 5. The lifting mechanism of claim 4, wherein the first and second brackets each have opposing planar surfaces and a top edge, and further comprising: a vertical brace affixed to the bed platform and spanning between facing planar surfaces of the first and second brackets; and a channel brace affixed to the bed platform and positioned to abut the top edges of the first and second brackets.
 6. A lifting mechanism for a bed deck having a top surface where a user may lie thereon and a bottom surface, the bed deck being rotatably mounted with a bed platform having a recessed storage area for movement of the bed deck from a horizontal to a non-horizontal position, the lifting mechanism being at least partially disposed in the recessed storage area, and comprising: a torsion bar; a cam follower rigidly mounted on the torsional bar; means for mounting the torsional bar with the bed platform; and a cam mounted to the bottom surface of the bed deck whereby a torsional force in the torsion bar generated by the rotation of the cam follower about an axis of the torsion bar and relative to a point on the torsion bar spaced from the mounting with the cam follower is transferred by the cam follower to the cam to provide a biasing force to the bed deck in the direction of rotation thereof from the horizontal to the non-horizontal position.
 7. The lifting mechanism of claim 6, further comprising an anchor arm rigidly mounted on the torsional bar at the point on the torsion bar spaced from the mounting with the cam follower.
 8. A lifting mechanism for a bed deck having a top surface where a user may lie thereon and a bottom surface, the bed deck being rotatably mounted with a bed platform having a recessed storage area for movement of the bed deck from a horizontal to a non-horizontal position, the lifting mechanism comprising: a torsion bar; a cam follower rigidly mounted on the torsional bar; an anchor arm rigidly mounted on the torsional bar at a position spaced from the cam follower; means for mounting the torsional bar with the bottom surface of the bed deck; and a cam mounted to a base surface of the bed platform whereby a torsional force in the torsion bar generated by the cam follower pressing against the cam as the cam follower rotates about an axis of the torsion bar and relative to the position of the anchor arm provides a biasing force to the bed deck in the direction of rotation thereof from the horizontal to the non-horizontal position. 